A UV LED is referred to as an LED having an emission wavelength in a UV range. The emission wavelength of UV LED may be classified into a long wavelength (i.e., UVA) having a wavelength ranging from 315 nm to 400 nm, a medium wavelength (i.e., UVB) having a wavelength ranging from 280 nm to 315 nm, and a short wavelength (i.e., UVC) having a wavelength less than 280 nm.
A short-wavelength UV LED has a wavelength range near to that of X-ray, and thus the short-wavelength UV LED is referred to as a deep UV LED, which in recent years has been primarily made of a light emitting material containing aluminum gallium nitride (AlGaN).
However, the deep UV LED made of the light emitting material containing AlGaN usually has a problem of producing a relatively high voltage due to difficulty in doping with magnesium resulting from an increasing amount of aluminum, and problems of electron leakage and inferior hole-injection efficiency, such that the light-emission performance is affected. Therefore, there is a room for further improvement in light emission efficiency and light extraction efficiency for the deep UV LED die.
In view of the aforesaid, an important research goal of the disclosure is to further develop or design a deep UV LED which effectively enhances light emission efficiency and light extraction efficiency.